: 5 3 TRAVELS TO DISCOVER 



half, was not really made by him, but was fome old Chal- 

 daic, or Egyptian obfervation, made by more instructed astro- 

 nomers which he had fallen upon. 



The Arabs call it ASTouan, which they fay Signifies enlight- 

 ened; in allufion, I fuppofe, to the circumstance of the well, 

 enlightened within by the fun's being Stationary over it in 

 June; in the language of Beja its name Signifies a circle, or 

 portion of a circle. 



Syene, among other things, is famous for the firft attempt 

 made by Greek aStronomers to afcertain the meafure of the 

 circumference of the earth. Eratofthenes, born at Cyrene a- 

 bout 276 years before ChriSt, was invited from Athens to A- 

 lexandria by Ptolemy Evergetes, who made him keeper of 

 the Royal Library in that city. In this experiment two po- 

 fitions were aSTumed, that Alexandria and Syene were ex- 

 actly 5000 Stades diftant from each other, and that they were 

 precifely under the fame meridian. Again, it was verified by 

 the experiment of the well, that, in the fummer folftice at 

 mid-day, when the fun was in the tropic of Cancer, in its 

 greateft northern declination, the well* at that inStant was 

 totally and equally illuminated ; and that no Style, or gno- 

 mon, erected on a perfect plane, did caSt, or project, any 

 manner of Shadow for 150 Stades round, from which it was 

 juStly concluded, that the fun, on that day, was fo exactly 

 vertical to Syene, that the center of its diSk immediately cor- 

 refponded to the center of the bottom of the well. Thcfe 

 preliminaries being fixed, Eratofthenes fet about his obfer- 

 vation thus : — 



On 



* Strabo, lib. ii.p. 133. 



